Polystyrene microplastics induce autophagy and apoptosis in birds lungs via PTEN/PI3K/AKT/mTOR.

Microplastics (MPs) seriously pollute and potentially threaten human health. Birds are sentinels of environmental pollutants, which respond quickly to contamination events and reveal current environmental exposure. Therefore, birds are good bioindicators for monitoring environmental pollutants. However, the mechanism of lung injury in birds and the role of the PTEN/PI3K/AKT axis are unknown. In this study, broilers treated with different polystyrene microplastics (PS-MPs) (0, 1, 10, and 100 mg/L) were exposed to drinking water for 6 weeks to analyze the effect of PS-MPs on lung injury of broilers. The results showed that with the increase of PS-MPs concentration, malonaldehyde (MDA) content increased, and catalase (CAT) and glutathione (GSH) activity decreased, further leading to oxidative stress. PS-MPs caused the PI3K/Akt/mTOR pathway to be inhibited by phosphorylation, and autophagy accelerated formation (LC3) and degradation (p62), causing autophagy. In PS-MPs exposed lung tissues, the expression of Bax/Bcl-2 and Caspase family increased, and MAPK signaling pathways (p38, ERK, and JNK) showed an increase in phosphorylation level, thus leading to cell apoptosis. Our research showed that PS-MPs could activate the antioxidant system. The antioxidant system unbalance-regulated Caspase family, and PTEN/PI3K/AKT pathways initiated apoptosis and autophagy, which in turn led to lung tissue damage in chickens. These results are of great significance to the toxicological study of PS-MPs and the protection of the ecosystem.